Multivalent Theranostics for Vascular Imaging and Therapy Project Summary Non-invasive approaches for functional assessment of atherosclerosis present an opportunity for intervention in cardiovascular disease. In our preliminary studies, we have successfully employed multimodal vesicles (fluorescence and magnetic resonance imaging, MRI) containing key engulfment ligands of M to enable preferential imaging of these cells in atherosclerosis. Our method takes advantage of macrophage engulfment of agents, allowing prolonged retention of MRI signal in the atherosclerotic vessel wall. In this proposal, we hypothesize that immunoliposomes based on these principles containing antibodies against myeloid related protein-8/14 (MRP), shown to be a key mediator of inflammation and injury by our group, will facilitate imaging, alter M phenotype, enhance anti-inflammatory effects, while minimizing off-target side effects of therapeutic agents. In this proposal we suggest a series of structured studies in relevant models of inflammation and atherosclerosis (ApoE-/- and ApoE-/-MRP14-/-). In Aim 1, we will test the ex-vivo and in-vivo theranostic properties of PEG protected Gd-containing fluorescently-tagged immunoliposomes against MRP (antiMRP-CC- L). Spatial localization, targeting and optimization will be carried out in organoid cultures and short-term wire- injury models. In Aim 2, we will synthesize and test theranostic immunoliposomes and hypothesize that immunoliposomes validated in Aim 1 and additionally containing a PPAR agent (-antiMRP8/14-CC-L) represents an attractive approach that combines locus specific delivery with synergistic therapeutic effects of PPAR agents on M function. As part of this aim, we will investigate biodistribution and pharmacokinetics of several doses of an optimized -antiMRP-CC-L in ApoE-/- and will additionally test the feasibility of in-vivo imaging in inflammation. The effects on M phenotype and function will be evaluated by assessing M surface markers, cytokines and inflammatory gene expression. We propose well designed experiments that will allow assessment of imaging performance, therapeutic effects including mechanisms of action that will shed unique insights into the roles of MRP and therapeutic synergism with M specific delivery of high-affinity PPAR ligands. The utilization of clinically approved Gd preparations, high Gd-payload/particle and homology of MRP in mice and humans confers immediate translational relevance. We envision that strategies combining M targeted imaging probes and therapies has the potential for use in a variety of inflammatory diseases.